To predict the behaviour of materials used, in particular their stability over time when they are subjected to high temperatures, conventionally initial tests are conducted in laboratory conditions wherein they are subjected to a thermal cycle, according to predefined profiles of temperature variation, in a predetermined environment simulating to the best the harsh environmental conditions encountered during the aforementioned space missions: exposure to UV, VUV, EUV radiation, to X rays or even to elementary particles: electrons or protons, and to do so under high vacuum.
To achieve this objective, samples of materials are arranged generally on supports, for example on plates in a chamber having a high vacuum and are subjected to programmed heating cycles.
When tests are conducted on sample materials, the precise measurement of their temperatures, which can be taken at different points of their surface, is therefore of primordial importance.
These temperatures depend on numerous factors and parameters, such as the thermal contacts with their supports, the source of heat used, the absorption of energy particles, etc. Furthermore, the measurements can be distorted by the environment or can present different types of artifacts.
These parameters are particularly critical when tests are conducted on samples of materials of slight thickness, such as films. These tests conducted on said samples are very interesting, since they represent real standard situations: surface deposits, paint, textures, etc. The thickness of these films typically falls within the 7 to 50 μm range. In the latter case, it is evident that the quality of the thermal contact between the sample material's film and its support constitutes a major unknown factor during the test process, particularly since this thermal contact varies greatly from one sample to another.
The precision of measurements recorded also depends on the type of measurement device used and its precision.
It follows that the temperature reached by the samples of materials could, up until now, only be measured with a relative precision, incompatible with the necessities inherent in the applications concerned by the invention.